A exploraÃÃo de Ãreas de emprÃstimo para obtenÃÃo de materiais para obras civis tem resultado na degradaÃÃo ambiental, muitas vezes, com sÃrios impactos nos meio fÃsico e biÃtico. Assim, os impactos ambientais de Ãreas de emprÃstimo devem ser identificados, para que sejam propostas e executadas medidas visando à sua recuperaÃÃo. Neste trabalho, procurou-se avaliar a eficÃcia das medidas mitigadoras propostas nos estudos de impacto ambiental dos aÃudes pÃblicos Aracoiaba e SÃtios Novos, no estado do CearÃ, para a recuperaÃÃo das Ãreas degradadas durante a obtenÃÃo de matÃria prima para suas obras civis. A pesquisa teve inÃcio com o levantamento dos EIA/RIMA dos AÃudes PÃblicos Aracoiaba e SÃtios Novos, com Ãnfase na anÃlise dos impactos identificados como possÃveis de ocorrerem nas Ãreas de emprÃstimo dos dois empreendimentos. Foram tambÃm levantadas as medidas mitigadoras propostas para recuperaÃÃo das Ãreas de emprÃstimos dos dois reservatÃrios. A partir de pesquisas de campo foi realizado levantamento das medidas mitigadoras efetivamente implantadas para recuperaÃÃo das Ãreas de emprÃstimo. A pesquisa permitiu a realizaÃÃo de estudo comparativo entre as medidas propostas e as efetivamente implantadas nas Ãreas de emprÃstimo dos dois aÃudes. Constatou-se que vÃrias medidas propostas nÃo foram implantadas, principalmente nas Ãreas de emprÃstimo do AÃude SÃtios Novos, resultando na existÃncia de Ãreas ainda degradadas, necessitando de recuperaÃÃo. Ao final, propÃe-se a adoÃÃo de aÃÃes visando mitigar a degradaÃÃo ambiental resultante dos dois aÃudes, nas suas Ãreas de emprÃstimo. / Exploitation of borrow areas to obtain materials for civil works has resulted in environmental degradation , often with serious impacts on physical and biotic environment . Thus , the environmental impacts of borrow areas should be identified , to be proposed and implemented measures aimed at their recovery . In this study, we sought to assess the effectiveness of mitigation measures proposed in the environmental impact studies and public dams Aracoiaba Novos , in the state of Cearà , for the recovery of degraded areas for obtaining feedstock for its civil works . The research began with a survey of the EIS / EIR for Public and Sites New Dams Aracoiaba , with emphasis on the analysis of the impacts identified as possible to occur in the areas of loan of two developments . Were also raised proposals for the rehabilitation of the two reservoirs loans mitigation measures . From field research was conducted survey of mitigation measures effectively implemented for the rehabilitation of loan. The survey allowed for a comparative study between the proposed measures and effectively implemented in the areas of borrowing of the two dams . It was observed that several proposed measures were not implemented , mainly in the areas of loan Novos Dam, resulting in the existence of yet degraded areas needing recovery . At the end, we propose the adoption of actions to mitigate environmental degradation resulting from the two dams in their lending areas.

Fuel cells are known for their high efficiency and have the potential to become a major technology for producing clean energy, especially when the fuel, e.g. hydrogen, is produced from renewable energy sources such as wind or solar. Currently, the two main obstacles to wide-spread commercialization are their high cost and the short operational lifetime of certain components. Polymer electrolyte membrane (PEM) fuel cells have been a focus of attention in recent years, due to their use of hydrogen as a fuel, their comparatively low operating temperature and flexibility for use in both stationary and portable (automotive) applications. Perfluorosulfonic acid membranes are the leading ionomers for use in PEM hydrogen fuel cells. They combine essential qualities, such as high mechanical and thermal stability, with high proton conductivity. However, they are expensive and currently show insufficient chemical stability towards radicals formed during fuel cell operation, resulting in degradation that leads to premature failure. The incorporation of durability improving additives into perfluorosulfonic acid membranes is discussed in this work. iv Cerium oxide (ceria) is a well-known radical scavenger that has been used in the biological and medical field. It is able to quench radicals by facilely switching between its Ce(III) and Ce(IV) oxidation states. In this work, cerium oxide nanoparticles were added to perfluorosulfonic acid membranes and subjected to ex-situ and in-situ accelerated durability tests. The two ceria formulations, an in-house synthesized and commercially available material, were found to consist of crystalline particles of 2 – 5 nm and 20 – 150 nm size, respectively, that did not change size or shape when incorporated into the membranes. At higher temperature and relative humidity in gas flowing conditions, ceria in membranes is found to be reduced to its ionic form by virtue of the acidic environment. In ex-situ Fenton testing, the inclusion of ceria into membranes reduced the emission of fluoride, a strong indicator of degradation, by an order of magnitude with both liquid and gaseous hydrogen peroxide. In open-circuit voltage (OCV) hold fuel cell testing, ceria improved durability, as measured by several parameters such as OCV decay rate, fluoride emission and cell performance, over several hundred hours and influenced the formation of the platinum band typically found after durability testing.